Android Emulator Screen Goes Blank After Pressing a Button

Question

I have created a small project in android, I have come to the point where after loading my app on the emulator, I press one of the buttons and it just shows a blank screen. I don't know why it is doing this. Any Help is welcome.

Here is my main Class:

     import android.os.Bundle;
     import android.app.Activity;
     import android.content.Intent;
     import android.view.Menu;
     import android.view.View;
     import android.view.View.OnClickListener;
     import android.widget.Button;

    public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);         
          Button Button1=(Button)findViewById(R.id.Button1);
          Button1.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                    Intent i = new Intent(MainActivity.this,ActivityList.class);
                    startActivity(i);
            }}
            );
          }
}

This is my XML Manifest File:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sportsfitnessapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity android:name=".ActivityList" />
        <activity
            android:name="com.example.sportsfitnessapp.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

I really need help. Thanks.

This is the Main XML Layout:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/widget35"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/background"
    tools:context=".Screen1Activity" >

    <TextView
        android:id="@+id/Menutxt"
        android:layout_width="300dp"
        android:layout_height="65dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:background="#ffffffff"
        android:gravity="center"
        android:text="@string/Menu"
        android:textColor="#ffff0033"
        android:textSize="50sp"
        android:textStyle="bold|italic"
        android:typeface="serif" />

    <Button
        android:id="@+id/Button1"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/Menutxt"
        android:layout_below="@+id/Menutxt"
        android:layout_marginTop="20dp"
        android:gravity="center"
        android:text="@string/Choose_Activity"
        android:textColor="#ffffffff"
        android:textSize="25sp"
        android:typeface="serif"
        android:onClick="Button1"/>

    <Button
        android:id="@+id/Button5"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/Button1"
        android:layout_below="@+id/Button1"
        android:gravity="center"
        android:text="@string/Graphical_Records"
        android:textColor="#ffffffff"
        android:textSize="25sp"
        android:typeface="serif" />

    <Button
        android:id="@+id/Button4"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/Button5"
        android:layout_below="@+id/Button5"
        android:gravity="center"
        android:text="@string/Training_Schedule"
        android:textColor="#ffffffff"
        android:textSize="25sp"
        android:typeface="serif" />

    <Button
        android:id="@+id/Button2"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/Button4"
        android:layout_below="@+id/Button4"
        android:gravity="center"
        android:text="@string/Weight_Tracker"
        android:textColor="#ffffffff"
        android:textSize="25sp"
        android:typeface="serif" />

    <Button
        android:id="@+id/Button3"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/Button2"
        android:layout_below="@+id/Button2"
        android:gravity="center"
        android:text="@string/Heart_Rate_Monitor"
        android:textColor="#ffffffff"
        android:textSize="25sp"
        android:typeface="serif" />

</RelativeLayout>

And this is the ActivityList Class:

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class ActivityList extends Activity{

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }
                public void onClick(View v) {
                Intent i = new Intent();
                setContentView(R.layout.activities_list);
                startActivity(i); 
            }
        {;
    }

}

This is the Activities List XML:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:id="@+id/widget0"
    android:background="@drawable/background" >

<Button
    android:id="@+id/Treadmill"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Weights"
    android:layout_below="@+id/ActTxt"
    android:gravity="center"
    android:text="@string/Treadmill"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<Button
    android:id="@+id/Aerobics"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Treadmill"
    android:layout_below="@+id/Treadmill"
    android:gravity="center"
    android:text="@string/Aerobic_Steps"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<Button
    android:id="@+id/Cycling"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Aerobics"
    android:layout_below="@+id/Aerobics"
    android:gravity="center"
    android:text="@string/Cycling"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<Button
    android:id="@+id/Swimming"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Cycling"
    android:layout_below="@+id/Cycling"
    android:gravity="center"
    android:text="@string/Swimming"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<Button
    android:id="@+id/Rowing"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Swimming"
    android:layout_below="@+id/Swimming"
    android:gravity="center"
    android:text="@string/Rowing"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<TextView
    android:id="@+id/ActTxt"
    android:layout_width="300dp"
    android:layout_height="55dp"
    android:layout_alignLeft="@+id/Treadmill"
    android:layout_alignParentTop="true"
    android:layout_marginTop="16dp"
    android:background="#ffffffff"
    android:gravity="center"
    android:text="@string/Activities"
    android:textColor="#ffff0033"
    android:textSize="50sp"
    android:typeface="serif" />

<Button
    android:id="@+id/ETrainer"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_alignLeft="@+id/Rowing"
    android:layout_below="@+id/Rowing"
    android:gravity="center"
    android:text="@string/Elliptical_Trainer"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

<Button
    android:id="@+id/Weights"
    android:layout_width="300dp"
    android:layout_height="45dp"
    android:layout_below="@+id/ETrainer"
    android:layout_centerHorizontal="true"
    android:gravity="center"
    android:text="@string/Free_Weights"
    android:textColor="#ffffffff"
    android:textSize="25sp"
    android:typeface="serif" />

</RelativeLayout>

Answer 1

You start a new activity, ActivityList by the code:

Intent i = new Intent(MainActivity.this,ActivityList.class);
startActivity(i);

And I am pretty sure you have not done:

setContentView(R.layout.layout_for_your_activity_list);

In your onCreate(Bundle savedInstanceState) .

Example:

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_list); 
}

---

Actually you have the code present but you need to move the line

setContentView(R.layout.activities_list);

up into

onCreate(Bundle savedInstanceState)

just like in the example I gave you.

And please follow convention.

Button Button1=(Button)findViewById(R.id.Button1);

should be:

Button buttonOne = (Button) findViewById(R.id.button_one);

Use indentation. And the ugliest one in ActivityList :

{;
}

Remove it at once.

Answer 2

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(R.layout.activities_list);
}

use the above code in ActivityList

Answer 3

Check whether you are using any permissions or not. If yes, include them in your manifest file. For example -

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

I too had the same problem. This solution fixed it. Not only adding required permissions, but also check whether are there any serious warnings in your xml files, which also be reason for your problem.

Answer 4

Yuo have assigned onClick listener for button1.OnClick of that you are starting new activity that is "ActivityList.class". So when you click on that button new activity will be created and contents in that activity will be displayed. If there is no contents in the "ActivityList" empty screen will be displayed.